The video shows a young hippo chasing the crocodile in a watering hole, before the reptile flees the water with the hippo at its tail. The video ends with a group of elephants chasing the hippo away from its would-be playmate.

While Harris and her husband interpreted the hippo’s behaviour as playful, many of the viewers on Nikela’s YouTube page thought the hippo was trying to chase the crocodile away.

“From our perspective, it looked like he was just being playful with the crocodile and just kind of swimming around the water hole and he just wouldn’t leave him alone until finally the crocodile just got out,” she said.

Because the hippo didn’t display any signs of aggression, it was probably just trying to play, said Jen Guyton, a National Geographic Explorer who is studying mammal ecology and conservation in Mozambique.

“It’s recognisable to anyone that’s ever spent time with a dog, for example, as play behaviour and it’s because that type of behaviour is pretty consistent across mammals,” she said.

It is somewhat unusual to see a mammal playing with a reptile, because mammals most often play within their own species.

“It could be that maybe there weren’t any young hippos around to play with, but I think the more likely thing is that sometimes mammals will play with objects or other species in their environment just out of curiosity,” said Guyton. (Watch an elephant invite a rhino to play.)

Before she started shooting video, Harris also saw the same hippo playing with a pipe.

Crocodiles often prey on hippo calves, but luckily this hippo was large enough to escape an unfortunate fate, Guyton said.

“It could be really beneficial to this hippo because if it was a female hippo, she might want to have a calf of her own and then she might recognise the crocodile as a threat,” said Guyton. “Having played with crocodiles when she was younger, she now has some idea of how they behave or how they react.”